Liquid crystal display devices, which are one of the display devices, have been widely used in mobile devices, such as laptop computers and cellular phones, as well as in audio-visual devices, such as liquid crystal display televisions, because they are thin and light.
Generally, liquid crystal display devices are provided with a pair of substrates provided facing each other (namely, an active matrix substrate and an opposite substrate), a liquid crystal layer provided between the pair of substrates, and a sealing material provided in a frame shape to adhere the pair of substrates to each other and encapsulate liquid crystal between the two substrates.
Also, as such liquid crystal display devices, there are active matrix liquid crystal display devices, for example, which are provided with an active element, such as a TFT (Thin Film Transistor), corresponding to each pixel area, and connect a wiring that is provided on an insulating substrate, such as a glass substrate, to a pixel electrode that is provided on each pixel area through the aforementioned active element. These active matrix liquid crystal display devices are configured such that the wiring and the pixel electrode are connected through the active element provided between them, and that a potential applied from the wiring to the pixel electrode is controlled by the active element.
Here, in liquid crystal display devices, a prescribed pattern structure needs to be formed in order to form the wiring, pixel electrode or the like. However, patterning errors may occur while forming this pattern structure.
For example, when manufacturing an active matrix substrate provided with a plurality of switching elements, first, as shown in FIG. 16, an interlayer insulating film 102 is formed on an insulating substrate 100 on which switching elements (not shown in the figure) and a metal wiring 101 are formed.
Then, as shown in FIG. 17, a pixel electrode material 103 made of ITO (Indium Tin Oxide), for example, is formed on the entire insulating substrate 100 on which the metal wiring 101 and the interlayer insulating film 102 are formed.
Next, as shown in FIG. 18, a photosensitive resin 104 is disposed on the pixel electrode material 103. Then, as shown in FIG. 19, a resist 105 having a prescribed pattern is formed by exposing and developing this photosensitive resin 104.
Here, as shown in FIG. 18, because shapes corresponding to edge sections 101a on both widthwise ends of the metal wiring 101 on the lower layer appear as is on the photosensitive resin 104, light may be scattered at the edge sections 104a of the photosensitive resin 104 while the photosensitive resin 104 applied on the pixel electrode material 103 undergoes exposure, causing the exposure amount applied to the photosensitive resin 104 to be insufficient. As a result, the photosensitive resin 104 is not removed completely on the edge sections 104a of the photosensitive resin 104, leaving a residue 106 of the resist 105, as shown in FIG. 19.
Next, using the resist 105 as a mask, a pixel electrode 107 having a prescribed pattern is formed by etching. Here, because the residue 106 of the resist 105 is formed, the pixel electrode in aforementioned edge sections is not removed by etching, as shown in FIG. 20, resulting in a residue 108 of the pixel electrode 107. Thus, on edge sections 102a of the interlayer insulating film 102 where, by design, the pixel electrode 107 should have been removed, the pixel electrode 107 is not removed, and a residue 108 of the pixel electrode 107 is left in regions where the prescribed pattern is not formed, causing a so-called film residue. As a result, there has been a problem of the residue 108 electronically connecting adjacent pixels, causing an electrical short-circuit (leakage) and display anomalies, which significantly lower the display quality.
Therefore, methods for preventing a short-circuit between pixels and eliminating display anomalies have been suggested. More particularly, for example, there has been disclosed a method by which a pixel electrode is provided to form a film on a thin film that has been patterned into a prescribed shape on a transparent insulating substrate, and then, the pixel electrode is etched into a prescribed shape by performing dry etching using an ion beam milling method, where the ion beam incident angle is changed in two steps. It is disclosed that, by shifting between two ion beam incident angles, a film residue on an edge section of steps on the lower layer can be protected, and a short-circuit between pixels can be prevented, thereby improving the display quality (see Patent Document 1 for example).